Milling cutter



C. G. OLSON. MILLING CUTTER.

v 920. 1.425,93., Patented Aug. 15, 1922.

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Patented Aug. l5,1922.

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[67W] ZSO'W/ AUNITED STATESPATENT ori-fica.

CARL G. OLSON, OF CHICAGO, ILLINOIS, ASSIGNOR TO ILLINOIS TOOL WORKS, 0l' CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

MILLING CUTTER.

G. 0LsoN, a

`right angles to the axis of the cutter.

Usually these cutters are shorter than the len h of the saw and hencehave to be repositioned a number of times. This is disadvantageous because it is difficult to reposition the cutter accurately and the result is that thev saw teeth are very apt to be imperfect. Sometimes a number of these cutters are placed end toend on a mandrel and thus produce a composite or sectional'cutter of the same length as the saw; but it is difficult to make cutters exactly alike and to accurately position them on the mandrel land the saw teeth are just as'laptto be imperfect as when a single cutter is used.- The ultimate object of my invention is to facilitate the production of perfectA lhack saws and to render it practicable asla manufacturing proposition to produce perfect saws without requiring great ,skill and care on the part of the operator.. Viewed in another aspect, the object of the invention is to make it possible to Vproduce one,piece ring, milling cutters of any desired length bv the use of -a single turning tool of 'shorter' length than the cutter without the need of repositioning the tool in the senseofshifting ,it manually in a direction parallel to the axis of the cutter. In carrying out my invention I produce milling cutters in which the cutting faces of the teeth occur in rings, but they also occur in helices with the result that they/may be generated by a turning'tool traveling axially relatively to the cutter. In such case the cut which the turning tool takes continues from one end of the cutter to the other,'thus making it possible to produce a cutter of any desired length and with teeth which are all of exactly the same height. It has been ,common practice in cutting hack saws to cut first one side of a tooth and then the other, for example, first Specification of Letters Patent. Patnted Aug. 15, 1922. Application led October 20, 1920. i Serial N0.`418,143.

taking a cut on the acting side of the saw tooth and then on the relief side,alter nately this method producin better teeth 1n the saw. My cutter is adapted to operate in thls manner. To briefiy describe the method of producing my cutter: I take a slngle or multiple nosed turning tool and mount it in a relieving machine of thel type ordinarily employed in the production of gear cutting hobs. I also mount in the work holder of the machine a gashed blank of any desired length, usually the full length of the hack saw or` otherY work to be produced. Relieving machines' are well known is a common pitch in hack saws and usually in such cases, especially as it is desirable to cut first one side of the saw tooth and then `the other, -I would ordinarily employ a blank having 12 gashes and six threads or starts.

When theemachine is properly .geared andv the'work and turning tool mounted therein I start the machine, which causes the blank to rotate about its axis and the tool to travel in an axial direct-ion, that is, parallel to the axis vof the` blank. I feed the tool radially inward toward the blank to take the proper depth of cut, after; which tli'e raction will be automatic in the sense that the cut will `continue from one end of the blank toy the other,y the tool being automatically moved radially inward and outward to produce the relief in the cutter teeth in the mannerwell known to those familiar with the manufacture of hobs andmilling cutters. Usually it is necessary totake a number of cuts to reach the requisite depth, but after the blank has Hbeen cut to ,the proper depth along one helix I index the work by rotating it about its axis through the proper angle while the tool stands still. The cutting operation will then be repeated. and a second helix be produced. This operation is repeated for every helix to be cut. In other words, the work will be angularly advanced or indexed as many times as there are threads or starts to be produced ioo in my finished cutter. It will thus be seen that in taking each cut the turning tool travels from one end of the cutter blank to the other with the result that the cut is uniform from one end to the other. I would point out also that while a manual adjustment is necessary for each new cut or start, this adjustment does not consist as heretofore in shifting the tool lengthwise of the axis of the work (which on account of backlash and for other reasons requiresY great skill and care if the operation `is to be done at all accurately). The adjustment consists of indexing the work, that is, rotating it through the proper angle. Relieving and screw cutting machines are commonly provided with indexing heads so that the act of indexing can be performed easily and accurately. The result is that a cutter embodying my invention may be readily made accurately regardless of its length and of the number of threads or helices which it may have. Furthermore, by my method the number of adjustments required may be smaller than would be the case if an attempt were made to make an ordinary ring milling cutter of equal lengthv by the use of an ordinary turning tool. For example, no matter how long the cutter blank, a saw havin twelveteeth tothe inch may be produce by a milling cutter having but six threads or starts, and in such case the work need be indexed but six times.

-While my cutter is not necessarily limited to the production of hack'saws, it is nevertheless well adapted for such purpose and I have chosen to illustrate the invention as applied to the manufacture of hack saws. In the form selected:

Figure 1 is a face View of a cutter embodying the invention, the cutter being shown in the act of producing a hack saw.

Figure 2 is a fragmentary diagrammatic view illustrating the alternate manner in which the teeth of the cutter cut the teeth in the blank. In other words this is a profile view showing teeth on opposite sides of a given gash and illustrating the staggered relation of such teeth.

Figure 3 is an end view of my improved cutter showing the relief and other characteristics of the cutting teeth. 4

Figure 4 is a face view of a portion of the cutter, this view being on a llarger scale to more clearly illustrate the form and arrangement of the teeth.

Figure 5 is a diagrammatic view showing the profile of the cutter teeth and showing the generating tool in acting position.

Figure 6 is a diagrammatic View on an enlarged scale and with the helical lead exaggerated, the purpose being to bring out more clearly the principle underlying the arrangement and form of the teeth.

Figure 7 is a profile sectional view of a raaaeee multiple nose turning tool for producing a plurality of cutter teeth at a time.

Like numerals denote'like parts throughout the several views.

Referring to the drawings, l represents a saw blank and C indicates the cutter in general. rl`he cutter is preferably integral with arbol-s 2 at the ends whereby it is supported and rotated. The teeth 4 of the cutter are relieved in the usual manner and separated by gashes 6 as usual. rIhe cutting Afaces 4 have a profile illustrated by the turning tool 8 indicated in Figure 5. 'Ilie turning tool 8 shown in Figure 5 constitutes a single tool while the form 10 shown in Figure 7 constitutes a multiple toolthat is, one capable of cutting a plurality of teeth simultaneously. y

The teeth of my cutter are arranged both annularly and helically, that is to say, the cutting edges 4a are arranged in series one behind the other in rings the planes whereof are perpendicular to the axis of the cutter; but the bodyof each tooth conforms to a helix after the manner of an ordinary hob and the pitch of the helix is such that in any given helix the successive cutting vfaces will occur in different rings.

Referring to Figure 6 the rings are numbered ring l, ring 2, et. seq. and the rows of teeth between gashes are numbered row 1,'row 2, et. seq. The helices are also numbered helix 1, helix 2, et. seq. For identification I have numbered some of the teeth as No. l, No. 2, No. 3, et. seq. As the cutter is designed to cut first one side and then the other side of a tooth, I have marked the cutter teeth lR to indicate teeth which will cut the right side of a saw tooth and L to indi# cate those which will cut the left side of the same saw tooth. It will be noted by inspecting the diagram that the cutting edges of teeth No, 1R No. 2R and No. 3R`occur in ring No. 1, but they do not occur in the same helix. tains toot-h No. 1R, tooth No. 1L and tooth No. 14R, et. seq. As previously stated diack saws are frequently made 12 pitch. Accordingly the cutter here illustrated has twelve teeth in a circumference, but ,as each helix On the contrary, helix No. l concontains bothright7 and left cutting teeth, the number of helicesor threads is only six and hence the cutter blank-need be indexed but five times after the first setting. It will be understood that the shaded `parallelograms in Figure 6 represent the in a cutter for actual construction will appear approximately as shown in Figures 4 and 5.

In use my cutter is arranged with its axis parallel with the acting edges of a stack of blanks and is fed vertically down the.

stack, that is, in a direction parallel to the height of the stack and perpendicular to the plane of the individual blanks. The axis ofthe cutter moves parallel to itself and ordinarily completes the cutting of the entire stack `of blanks during a single pass or downward movement.

It might be thought that as the cutter has no axial travel when cutting the saw blanks, and as vthe bodies of theteeth are helical, the cutter would remove too much metal from 'the saw blanks, thus leaving no teeth at all or simply vestiges of teeth. This is not a fact, however, the reason being that the cutter teeth are relieved, that is,they drop down eccentrically back of the cutting face and hence there is no metal in the hob which will interfere with the saw teeth or prevent the perfect forming thereof. Y

From the foregoing it will be seen that a cutter embodyin my invention may be produced by a sing e or multiple cutting tool which is fed axiall relatively to the cutter; nevertheless w en the cutter is set to rotating it will produce saw teeth, for the cutting edges are arranged one directly behind the other in the same ring or plane perpendicular to the axis.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

l. A milling cutter having the cutting faces of its teeth arranged both helically and in rings perpendicular to the axis of the cutter.

2. A milling cutter having teeththe cutting faces whereof occur in rings parallel to the plane of rotation, and also in helices, and the body of the teeth being helical, whereby the cutter teeth may be generated by a turn-v ing tool traveling axia ly relatively to the cutter; and the cutter teeth being relieved for non-interference with the work.

3. A cutter for producing hack saws, the

cutter having a plurality of rings of teeth.

corresponding to the pitch of the teeth in the saw to be cut, the teeth of the cutter being also arranged and formed helically, as in an ordinary hob, and the pitch of the helix being such as to bring succeeding teeth in the helix into another ring on the cutter.

4. A cutter.. for produclng hack saws, the cutter having a plurality of rings of teeth, and a plurality of rows of teeth separated by gashes, the teeth being also arranged and formed helically, as in an ordinary hob, and the pitch of the helix being such as to bring eachsucceeding tooth in the helix-in the `next adjacent ring.

5. A cutter having helically arranged and helically formed teeth, the composite projection of the teeth on a reference plane parallel tothe axis presenting a complete outline of the work, and the projection of the teeth along any` given row being incomplete in that every other tooth is omitted.

A 6. A ring milling cutter having its teeth occurring in helices as well as rings and the helices being plural in number whereby the lead or helix angle is greatenough to bring the successive teeth in any given' helix into successive rings.

7. A ring milling cutter having its teeth occurring in helices as well as rings and the helices being plural in number whereby the lead or helix angle is great enough to bring 'the 'successive teeth in any given helix into successive rings and any givenpair of teeth occurring in helices as well as rings, and.

having the following arrangement and relative numbers and the actual numbers recited,

viz.; six helices; twelve teeth in a `,complete circumference in any given helix; six teeth in a complete circumference in any given ring; and twelve gashes; the profiles of any two adjacent teeth facing the same gash being separated by aspace cut to the root circle of the cutter and the distance between the points of the cutter being at a distance apart equal to the pitch of the teeth to be cut in the work.

10. A ring milling cutter having its teeth arranged in helices as well as rings, the cutter having a plurality of gashes and half as many helices as gashes.

In witness whereof, I have hereunto subscribed my name.

CARL G. oLsoN. 

